蛋白摂取量とダイナペニア：横断研究

蛋白摂取量とダイナペニアの関連を閉経後女性で調査した横断研究を紹介します。

M. E. Filion, et al: Relationship between protein intake and dynapenia in postmenopausal women. The Journal of Nutrition, Health & Aging 2012, DOI: 10.1007/s12603-012-0054-8

リサーチクエスチョンは以下の通りです。

P：閉経後の虚弱でない50-75歳の女性で
E：蛋白摂取量が多いと
C：蛋白摂取量が少ない場合と比較して
O：ダイナペニアを認めることが多い
D：横断研究

抄録しか読んでいないので詳細不明ですが、ダイナペニアをtype  I とtype IIに分類しています。おそらく筋力（今回は握力）が若年女性の平均値より1標準偏差以下の場合をtype I、2標準偏差以下の場合をtype II、としているのではないかと推測します。

結果ですが、ダイナペニアでない群とtype IIダイナペニア、およびtype Iダイナペニアとtype IIダイナペニアの間に、有意な蛋白摂取量の差を認めました。一方、ダイナペニアをkg/BWもしくはkg/LBMで判断した場合、3群間で除脂肪体重の量に有意差を認めませんでした。

以上より、蛋白摂取量とtype IIダイナペニアには有意な関連があるという結論です。横断研究ですので因果関係は不明ですし、72名と少人数かつ女性限定ですが、蛋白摂取量が多いほうがダイナペニアの予防に有利な可能性があります。今後の研究次第ですが。

Abstract

Objective

The purpose of this study was to investigate the relationship between protein intake and dynapenia.

Design

A cross-sectional/observational study.

Setting

Department of Kinanthropology at the University of Quebec at Montreal.

Participants

Seventy-two non-frail postmenopausal women aged between 50 to 75 years were recruited.

Measurements

Body weight (BW), lean body mass (LBM; %) and skeletal muscle mass (bio-electrical impedancemetry analysis), maximum voluntary handgrip strength (using hand dynamometer), aerobic capacity (VO2peak) and dietary intake were measured. Women were divided according to dynapenia criteria.

Results

The strongest correlation between muscle strength and protein intake was observed when we express the amount of protein in g/d/BW. No differences for age, BMI, status of menopause, fat mass and VO2peak were observed between non-dynapenic, type I dynapenic and type II dynapenic women, independently of the criteria used. We observed significant differences in protein intake (g/d/BW) between nondynapenic and type II dynapenic (p<0.01) as well as between type I dynapenic and type II dynapenic (p<0.01) when dynapenia was expressed in kg/BW and in kg/LBM, respectively. It should be noted that no differences in LBM between the three groups were observed when dynapenia was expressed in kg/BW and kg/LBM. Protein intake for all groups respected the RDA of 0.8 to 1.2 g/d/BW (non-dynapenic: 1.44/1.38; type I dynapenic: 1.30/1.33; type II dynapenic: 1.05/1.08 g/d/BW).

Conclusions

Protein intake seems to play a role in the development of dynapenia particularly at the level of type II dynapenia. Therefore, an increase in the recommended daily allowance for protein intake may be warranted.